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usb: gadget: uvc: decrease the interrupt load to a quarter 

With usb3 we handle many more requests. Decrease the interrupt load by
only enabling the interrupt every quarter of the allocated requests.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>

--
v1 -> v2: - edited patch description
	  - removed extra parantheses
	  - added a comment for the logic
	  - using unsigned int instead of int
	  - reinitializing req_int_count in uvcg_video_enable
v2 -> v3: -
Link: https://lore.kernel.org/r/20210628155311.16762-6-m.grzeschik@pengutronix.de

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Grzeschik 2021-06-28 17:53:11 +02:00 committed by Greg Kroah-Hartman
parent e81e7f9a0e
commit fc78941d81
2 changed files with 18 additions and 0 deletions
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2
drivers/usb/gadget/function/uvc.h
View File

@ -101,6 +101,8 @@ struct uvc_video {
struct list_head req_free;
spinlock_t req_lock;
unsigned int req_int_count;
void (*encode) (struct usb_request *req, struct uvc_video *video,
struct uvc_buffer *buf);

16
drivers/usb/gadget/function/uvc_video.c
View File

@ -360,6 +360,19 @@ static void uvcg_video_pump(struct work_struct *work)
video->encode(req, video, buf);
/* With usb3 we have more requests. This will decrease the
* interrupt load to a quarter but also catches the corner
* cases, which needs to be handled */
if (list_empty(&video->req_free) ||
buf->state == UVC_BUF_STATE_DONE ||
!(video->req_int_count %
DIV_ROUND_UP(video->uvc_num_requests, 4))) {
video->req_int_count = 0;
req->no_interrupt = 0;
} else {
req->no_interrupt = 1;
}
/* Queue the USB request */
ret = uvcg_video_ep_queue(video, req);
spin_unlock_irqrestore(&queue->irqlock, flags);
@ -368,6 +381,7 @@ static void uvcg_video_pump(struct work_struct *work)
uvcg_queue_cancel(queue, 0);
break;
}
video->req_int_count++;
}
spin_lock_irqsave(&video->req_lock, flags);
@ -416,6 +430,8 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
video->encode = video->queue.use_sg ?
uvc_video_encode_isoc_sg : uvc_video_encode_isoc;
video->req_int_count = 0;
schedule_work(&video->pump);
return ret;